| 摘要 |
963,898. Milling. KEARNEY & TRECKER CORPORATION. Feb. 21, 1961 [Oct. 14, 1960], No. 6299/61. Heading B3K. [Also in Division F2] In a screw-and-nut mechanism for moving a work-supporting table 18 of a milling machine, a lead screw 21 is journalled in the machine bed 10 and carries a pair of nuts 28, 28A located on opposite sides of an abutment 25 on the table 18, the nuts 28, 28A are interconnected for simultaneous rotation in opposite directions relative to the screw to effect their simultaneous axial movement toward and away from the abutment 25, and one-way clutches 30, 30A are arranged to release when the nuts are moved away from the abutment 25 in order to relieve the frictional engagement of the nuts with the abutment. The nuts 28, 28A are integral with gears 31, 31A which are interconnected through gears 61, 62, and a spring- pressed rack 72 meshes gear 61. The rack 72 is located in a bore 73 and has an adjustable end stud 77. When the screw 21 is driven in a counter-clockwise direction, as viewed from the left in Fig. 4, to effect rightward movement of the table, the conventional cutting force F urges the table 18 to the left, thereby causing the nut 28A to rotate with the screw 21 which, in turn, causes rotation of nut 28 to move it axially away from the abutment 25, thereby relieving tension in the portion of the screw 21 between the nuts 28, 28A. The rotation of the nuts 28, 28A is limited by the engagement of the rack stud 77 with the end of the bore 73, whereby the nut 28A is held against rotation in order to effect axial movement of the table 18. During a climb-cutting operation, the nuts 28, 28A tighten against the abutment 25. |
